This invention relates to a multi-cylinder combustion engine with gas exchange upper valves that are moved by electromagnetic actuators and that control the intake as well as the discharge of the cylinder combustion chambers. Reference is made to DE 196 11 547 A1, by way of example, regarding the technical environment.
An electromagnetic upper valve moving device for a combustion engine, also called electromagnetic actuator, offers tremendous advantages due to the freedom regarding the valve control times, that is to say, regarding the particular opening and closing moment of the upper valves; but for movement purposes, in particular, for the purpose of opening the upper valve, one must apply relatively strong forces and that necessitates a certain minimum size for the magnetic coils and the armature. As a result, it is extremely difficult to house the known actuators in a currently customary cylinder head, for example, in a combustion engine that drives a motor vehicle. This problem applies even more so in the case of combustion engines that have two or more intake valves or discharge valves per cylinder.
The invention at hand is intended to point out measures that will contribute to the solution of the complex problem just described.
The solution of this problem is characterized by the following: The cross-section surface of the actuators associated with the intake upper valves, which is positioned perpendicularly to the axial direction of the upper valves, is smaller than the corresponding cross-section surface of the actuators that are associated with the discharge upper valves. Advantageous forms and developments are covered in the subclaims.
The invention deviates from the hitherto-customary equal-parts concept; in other words, the following is proposed: In place of the hitherto-customary procedure, where equally dimensioned actuators were provided for the intake upper valves as well as the discharge upper valves, the actuators now are adapted to the particular upper valves to be moved in terms of their discharge capacity and thus also regarding their special geometric dimensions. It was found that to move an intake upper valve of a combustion engine, one requires less forces than for moving a combustion engine discharge upper valve. Here is the reason why: An opening motion of the intake upper valves is paralleled by an intake suction stroke of the combustion engine during which the cylinder volume, for example, in the case of a reciprocating piston combustion engine, is enlarged by the (so to speak, downward-directed) suction stroke of the cylinder piston. The resultant pressure drop supports an opening motion of the intake upper valves. On the other hand, when the discharge upper valves are opened, they are opened at the over-pressure that at this point in time still prevails in the cylinder, as a result of which, one can clearly understand that, upon the opening of a discharge upper valve, one must do more work than when the intake upper valve is opened.
The work capacity of an electromagnetic actuator that moves an upper valve is determined directly via the magnitude of the magnetic coils arranged in the actuator (including the sheet metal stampings as well as the armature that is moved in an oscillating manner between the magnetic coils and that in the final analysis acts upon the upper valve). This means that an actuator that must do less work can also have a smaller cross-section surface perpendicularly to the axial direction of the upper valve to be moved than an actuator that must perform comparatively heavier work. It is precisely this interrelationship that is shown in the characterizing features of claim 1.